Induced EMF - Does Voltage Change Matter?

[whitegheghe10]

Suppose now i have connected a solenoid with a dc power supply of 10V
When i increase the voltage to 20V the magnetic flux through the coil have increased
will emf be induced shortly to oppose the change?

what if i now change it to a 10V ac power supply
so will there always be induced emf to oppose the change?

I am not clear about whether emf will be induced as a result of change in flux just due to change in its own current or will it occur only when the change is cause by external agent ( for example pushing a bar magnet towards the solenoid)

 

[kuruman]

Suppose now i have connected a solenoid with a dc power supply of 10V
When i increase the voltage to 20V the magnetic flux through the coil have increased
will emf be induced shortly to oppose the change?

Yes.

what if i now change it to a 10V ac power supply
so will there always be induced emf to oppose the change?

Yes.

I am not clear about whether emf will be induced as a result of change in flux just due to change in its own current or will it occur only when the change is cause by external agent ( for example pushing a bar magnet towards the solenoid)

Both.